SoilR (version 1.2.107)

TwopFeedbackModel: Implementation of a two pool model with feedback structure

Description

This function creates a model for two pools connected with feedback. It is a wrapper for the more general function GeneralModel.

Usage

TwopFeedbackModel(
  t,
  ks,
  a21,
  a12,
  C0,
  In,
  xi = 1,
  solver = deSolve.lsoda.wrapper,
  pass = FALSE
)

Value

A Model Object that can be further queried

Arguments

t

A vector containing the points in time where the solution is sought.

ks

A vector of length 2 with the values of the decomposition rate for pools 1 and 2.

a21

A scalar with the value of the transfer rate from pool 1 to pool 2.

a12

A scalar with the value of the transfer rate from pool 2 to pool 1.

C0

A vector of length 2 containing the initial amount of carbon for the 2 pools.

In

A data.frame object specifying the amount of litter inputs by time.

xi

A scalar or data.frame object specifying the external (environmental and/or edaphic) effects on decomposition rates.

solver

A function that solves the system of ODEs. This can be euler or deSolve.lsoda.wrapper or any other user provided function with the same interface.

pass

if TRUE forces the constructor to create the model even if it is invalid

References

Sierra, C.A., M. Mueller, S.E. Trumbore. 2012. Models of soil organic matter decomposition: the SoilR package version 1.0. Geoscientific Model Development 5, 1045-1060.

See Also

There are other predefinedModels and also more general functions like Model.

Examples

#This example show the difference between the three types of two-pool models  
times=seq(0,20,by=0.1)
ks=c(k1=0.8,k2=0.00605)
C0=c(C10=5,C20=5)

Temp=rnorm(times,15,2)
WC=runif(times,10,20)
TempEffect=data.frame(times,fT=fT.Daycent1(Temp))
MoistEffect=data.frame(times, fW=fW.Daycent2(WC)[2])

Inmean=1
InRand=data.frame(times,Random.inputs=rnorm(length(times),Inmean,0.2))
InSin=data.frame(times,Inmean+0.5*sin(times*pi*2))

Parallel=TwopParallelModel(t=times,ks=ks,C0=C0,In=Inmean,gam=0.9,
xi=(fT.Daycent1(15)*fW.Demeter(15)))
Series=TwopSeriesModel(t=times,ks=ks,a21=0.2*ks[1],C0=C0,In=InSin,
xi=(fT.Daycent1(15)*fW.Demeter(15)))
Feedback=TwopFeedbackModel(t=times,ks=ks,a21=0.2*ks[1],a12=0.5*ks[2],C0=C0,
In=InRand,xi=MoistEffect)

CtP=getC(Parallel)
CtS=getC(Series)
CtF=getC(Feedback)

RtP=getReleaseFlux(Parallel)
RtS=getReleaseFlux(Series)
RtF=getReleaseFlux(Feedback)

par(mfrow=c(2,1),mar=c(4,4,1,1))
plot(times,rowSums(CtP),type="l",ylim=c(0,20),ylab="Carbon stocks (arbitrary units)",xlab=" ")
lines(times,rowSums(CtS),col=2)
lines(times,rowSums(CtF),col=3)
legend("topleft",c("Two-pool Parallel","Two-pool Series","Two-pool Feedback"),
lty=c(1,1,1),col=c(1,2,3),bty="n")

plot(times,rowSums(RtP),type="l",ylim=c(0,3),ylab="Carbon release (arbitrary units)", xlab="Time")
lines(times,rowSums(RtS),col=2)
lines(times,rowSums(RtF),col=3)
par(mfrow=c(1,1))